The use of hemoglobin based oxygen carriers (HBOCs) in medicine has enormous potential, one particular application that is being intensely investigated is the use of HBOCs in situations where there is a high risk of stroke and/or brain damage due to ischemia. Preliminary data obtained in dogs strongly suggest that ischemia/reperfusion injury to the brain can be reduced by perfusion with Biopure's ultrapurified HBOC, Hemopure R. The goal of this proposal is to establish the feasibility of clinical development of Hemopure as a neuroprotective agent. The aims of this proposal are to 1) test the hypothesis that Hemopure is neuroprotective; 2) develop a better understanding of the mechanism(s) responsible for the protective effect of Hemopure and 3) determine if the combination of Hemopure with an antioxidant or nitrosylation of Hemopure cysteine beta92 enhances the neuroprotective effect. These aims will be accomplished by examination of the effects of Hemopure on ischemia/reperfusion injury in a rat model utilizing transient occlusion of the middle carotid artery. The extent of injury will be assessed by histological and biochemical methods. Particular emphasis will be placed on the role of increased oxygenation and the interaction between NO and hemoglobin on the protective effect of reperfusion with Hemopure. PROPOSED COMMERCIAL APPLICATION: The use of Biopure's Hemopure as a neuroprotective agent has an estimated market of 300-500 million per year. This includes the use in surgeries (ie. cardiopulmonary bypass) where there is an established risk of CNS injury, general ischemia (ie. gas intoxication), in the acute treatment of patients suffering from stroke, and during resuscitation following cardiac arrest.